1. Field of the Invention
The present invention relates to pentafluorobutane compositions including 1,1,1,3,3-pentafluorobutane.
2. Description of the Related Art
Chlorine-based solvents and fluorine-based solvents have been widely used as, for example, flux cleaners, solvents for dry cleaning, degreasing cleaners, buffing cleaners, resist removing agents, or solvents for removing adhesion water. Chlorine-based solvents, however, are substances causing groundwater pollution, and fluorine-based solvents are substances causing ozone layer depletion; because of their environmental problems, the use thereof is becoming restricted. From these perspectives, new solvents that could be used instead of the above-described solvents have been proposed in various fields.
1,1,1,3,3-pentafluorobutane (365 mfc, chemical formula: C4H5F5) is one such solvent. 1,1,1,3,3-pentafluorobutane has superior characteristics in that it does not include chlorine in its molecular structure, its ozone depletion potential (ODP) is zero, it is low in toxicity, its global warming potential (GWP) is also small, and thus it is ecological and clean. Therefore, various kinds of solvents that employ 1,1,1,3,3-pentafluorobutane have been proposed. (See, for example, JP 6-322394 A, JP 7-188700 A, JP 2002-241796 A, and JP 2003-129090 A.)
1,1,1,3,3-pentafluorobutane, however, has a drawback in that, when it is used for cleaning in hostile environments such as for high-temperature cleaning or vapor degreasing, it may become unstable because of it being affected by the object to be cleaned made of metal such as iron, zinc, aluminum, copper, and brass. Therefore, proposals have been made to add some kind of stabilizer to 1,1,1,3,3-pentafluorobutane to avoid such draw backs. (See, for example, JP 6-166894 A, JP 6-166895 A, JP 2000-328095 A, and JP 11-152236 A.)
However, even when stabilizers disclosed in these references are added, there are situations where 1,1,1,3,3-pentafluorobutane cannot be sufficiently stabilized if it is recycled repetitively over a long period of time in hostile environments such as those for high-temperature cleaning, vapor degreasing, etc. The reason to this may be that hydrogen fluoride gas, which is generated due to gradual decomposition of 1,1,1,3,3-pentafluorobutane, causes negative effects, such as corrosion, with respect to the object to be cleaned such as metal. Therefore, 1,1,1,3,3-pentafluorobutane cannot be recycled repetitively over a long period of time in environments such as those for high-temperature cleaning, vapor degreasing, etc.